Quantifying the energetic contributions of desolvation and π-electron density during translesion DNA synthesis
作者:Edward A. Motea、Irene Lee、Anthony J. Berdis
DOI:10.1093/nar/gkq925
日期:2011.3
This report examines the molecular mechanism by which high-fidelity DNA polymerases select nucleotides during the replication of an abasic site, a non-instructional DNA lesion. This was accomplished by synthesizing several unique 5-substituted indolyl 2′-deoxyribose triphosphates and defining their kinetic parameters for incorporation opposite an abasic site to interrogate the contributions of π-electron density and solvation energies. In general, the Kd, app values for hydrophobic non-natural nucleotides are ∼10-fold lower than those measured for isosteric hydrophilic analogs. In addition, kpol values for nucleotides that contain less π-electron densities are slower than isosteric analogs possessing higher degrees of π-electron density. The differences in kinetic parameters were used to quantify the energetic contributions of desolvation and π-electron density on nucleotide binding and polymerization rate constant. We demonstrate that analogs lacking hydrogen-bonding capabilities act as chain terminators of translesion DNA replication while analogs with hydrogen bonding functional groups are extended when paired opposite an abasic site. Collectively, the data indicate that the efficiency of nucleotide incorporation opposite an abasic site is controlled by energies associated with nucleobase desolvation and π-electron stacking interactions whereas elongation beyond the lesion is achieved through a combination of base-stacking and hydrogen-bonding interactions.
本报告研究了高保真 DNA 聚合酶在无碱基位点(一种非指导性 DNA 损伤)复制过程中选择核苷酸的分子机制。这是通过合成几种独特的 5-取代吲哚基 2'-脱氧核糖三磷酸并定义其在脱碱基位点对面掺入的动力学参数来探究 π 电子密度和溶剂化能的贡献来实现的。一般来说,疏水性非天然核苷酸的 Kd、app 值比等排亲水类似物的测量值低约 10 倍。此外,含有较低 π 电子密度的核苷酸的 kpol 值比具有较高 π 电子密度的等排类似物慢。动力学参数的差异用于量化去溶剂化和π电子密度对核苷酸结合和聚合速率常数的能量贡献。我们证明,缺乏氢键能力的类似物充当跨损伤DNA复制的链终止子,而具有氢键功能基团的类似物在与脱碱基位点相对配对时会延伸。总的来说,数据表明,脱碱基位点对面的核苷酸掺入效率是由与核碱基去溶剂化和π电子堆积相互作用相关的能量控制的,而超出损伤的伸长是通过碱基堆积和氢键相互作用的组合实现的。